Horseshoe cloud explained

A horseshoe cloud is a relatively uncommon meteorological phenomenon^[1] which manifests as a cloud in the shape of a horseshoe or inverted letter "U".^[2]

They occur when a horseshoe vortex deforms a cumulus cloud. The clouds are relatively short-lived and is the last stage before one dissipates.^[3] Horseshoe vortex clouds are a form of "fair-weather" funnel cloud and are similar to the shear funnel type of funnel cloud.

A March 2018 instance was explained by the United States National Weather Service:^{[4] [5]}

These clouds do not occur often because all the needed conditions rarely occur together.

Notes and References

1. Web site: Horseshoe Vortex Cloud (February 07). January 31, 2007 . Cloud Appreciation Society. March 12, 2018.
2. Web site: An incredibly rare 'horseshoe cloud' was spotted in Nevada and it kept the meme-makers busy . Independent.ie . March 12, 2018 . March 12, 2018 .
3. Web site: Baer . Stephanie K. . People On Twitter Are Freaking Out Over This Rare Type Of Cloud . 2023-02-02 . BuzzFeed News . March 10, 2018 . en.
4. NWSElko . 972173128800628736 . As the updraft pushes flattish cumulus clouds up & a horizontal vortex develops from differential updraft speeds... .
5. NWSElko . 972173174422036490 . As the vortex climbs, it's caught in the faster horizontal winds aloft,& the middle part of the vortex catches the faster speeds with the ends being slower. .